Mass spectrometry (MS) is a very sensitive analytical method used for important research and for applications of analytical chemistry, such as life science. In the field of analytical chemistry, the demand for direct sampling under ambient conditions has increased. Direct sampling in the ambient environment (in situ) provides a sample analysis approach in which there is no intrinsic requirement for sample preparation, which allows real-time, on-site analysis of samples, saving time and resources.
To achieve direct sampling in an ambient environment, the sample must be efficiently transferred to the mass spectrometer because the sensitivity of mass analysis is highly dependent on the efficiencies of sample introduction to the mass spectrometer. For miniature mass spectrometry systems particularly, it is highly desirable to maximize the amount of the sample that can be introduced to the mass spectrometer.
A problem with sample introduction is that an MS inlet is very small, typically smaller than 700 μm, due to the fact that a vacuum must be maintained inside a manifold where ions are mass analyzed. Accordingly, the intake of neutral molecules or ions from atmosphere by the MS inlet is relatively inefficient, which hampers direct sampling from an ambient environment.